August is one of the warmer months of the year in Normal, with average highs near 28.5°C and lows around 17.2°C (mean 22.9°C). It is a relatively wet time of year, averaging 92 mm of rainfall and 73% relative humidity across the period.
August is one of the warmer months of the year in Normal. Across 45 years of records, the warmest August in Normal was 1988 — when the month averaged 26.6°C — while the coldest was 1992 at 18.9°C. Typical August days reach 28.5°C with nights near 17.2°C. The long-term trend is warming, about 0.2°C per decade.
August is a relatively wet time of year in Normal, averaging 92 mm of rainfall. The wettest August on record was 1981 with 205 mm, while the driest was 1984 at 26 mm.
Relative humidity in Normal during August averages 73%. The most humid August was 1993 at 86%, and the least humid was 1988 at 54%.
August receives about 5.5 kWh/m²/day of solar energy in Normal. The sunniest August was 2020 at 6.2 kWh/m²/day, and the cloudiest was 2014 at 4.7.
Average wind speed in Normal during August is 2.2 m/s. The windiest August was 2000 at 2.7 m/s, while the calmest was 1995 at 1.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 22.9°C | 22.1°C | 23.2°C | 23.0°C | 23.2°C | +0.3°C |
| Avg High | 28.9°C | 27.6°C | 29.0°C | 28.4°C | 29.0°C | +0.1°C |
| Avg Low | 16.9°C | 16.7°C | 17.5°C | 17.6°C | 17.5°C | +0.6°C |
| Avg Rain | 91 mm | 98 mm | 99 mm | 86 mm | 84 mm | -7 mm |
August temperatures in Normal have risen by about 1°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 6.3°C (1986) to a record high of 40.3°C (1988).
Rainfall in August is a relatively wet time of year, averaging 92 mm, with a wettest year of 205 mm.
One of the best times to visit Normal
August is one of the best times to visit Normal. Expect days averaging 28.5°C and nights around 17.2°C (mean 22.9°C) — warmer than Normal's yearly average — with higher rainfall (92 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 29.1°C | 23.0°C | 17.0°C | 34.3°C | 10.4°C | 52 mm | 69% | 2.1 m/s | 6 |
| 2024 | 29.2°C | 23.2°C | 17.3°C | 35.7°C | 9.5°C | 89 mm | 68% | 2.2 m/s | 5.8 |
| 2023 | 29.5°C | 23.3°C | 17.1°C | 37.6°C | 9.8°C | 98 mm | 70% | 2.2 m/s | 5.4 |
| 2022 | 29.7°C | 23.8°C | 17.8°C | 33.4°C | 12.5°C | 119 mm | 71% | 2.3 m/s | 5.5 |
| 2021 | 28.3°C | 23.6°C | 18.9°C | 32.3°C | 12.9°C | 111 mm | 80% | 2 m/s | 5.6 |
| 2020 | 28.0°C | 22.5°C | 16.9°C | 34.0°C | 12.7°C | 36 mm | 73% | 2 m/s | 6.2 |
| 2019 | 27.1°C | 22.2°C | 17.3°C | 30.5°C | 11.6°C | 63 mm | 80% | 2.2 m/s | 5.5 |
| 2018 | 29.6°C | 24.1°C | 18.6°C | 33.2°C | 13.5°C | 105 mm | 74% | 2.4 m/s | 5.4 |
| 2017 | 27.8°C | 21.6°C | 15.5°C | 33.8°C | 11.4°C | 76 mm | 69% | 2 m/s | 5.7 |
| 2016 | 27.7°C | 23.5°C | 19.2°C | 32.1°C | 14.1°C | 177 mm | 83% | 2 m/s | 5.4 |
| 2015 | 26.2°C | 21.3°C | 16.3°C | 30.2°C | 10.6°C | 67 mm | 80% | 2.2 m/s | 5.7 |
| 2014 | 28.1°C | 23.1°C | 18.1°C | 33.2°C | 11.4°C | 122 mm | 78% | 2.1 m/s | 4.7 |
| 2013 | 28.1°C | 22.5°C | 16.9°C | 35.1°C | 10.8°C | 33 mm | 75% | 1.9 m/s | 5.7 |
| 2012 | 31.5°C | 24.3°C | 17.2°C | 37.4°C | 11.5°C | 103 mm | 55% | 2 m/s | 5.7 |
| 2011 | 29.6°C | 23.6°C | 17.7°C | 35.3°C | 13.5°C | 40 mm | 72% | 2.1 m/s | 6 |
| 2010 | 28.6°C | 23.7°C | 18.9°C | 32.5°C | 12.4°C | 78 mm | 81% | 2 m/s | 6.1 |
| 2009 | 25.4°C | 20.7°C | 16.1°C | 30.4°C | 7.7°C | 123 mm | 83% | 2.4 m/s | 5.2 |
| 2008 | 26.5°C | 21.2°C | 15.9°C | 30.2°C | 11.4°C | 42 mm | 79% | 2.1 m/s | 5.9 |
| 2007 | 30.7°C | 25.3°C | 20.0°C | 35.8°C | 12.2°C | 105 mm | 74% | 2.3 m/s | 5.5 |
| 2006 | 29.0°C | 23.6°C | 18.3°C | 36.4°C | 13.4°C | 114 mm | 72% | 2.4 m/s | 4.9 |
| 2005 | 31.2°C | 25.1°C | 18.9°C | 36.2°C | 13.5°C | 75 mm | 64% | 2.1 m/s | 5.6 |
| 2004 | 26.8°C | 20.9°C | 14.9°C | 32.8°C | 9.0°C | 123 mm | 71% | 2.5 m/s | 5.3 |
| 2003 | 30.6°C | 24.3°C | 18.0°C | 38.6°C | 14.7°C | 99 mm | 67% | 2.3 m/s | 5.6 |
| 2002 | 28.1°C | 22.8°C | 17.5°C | 32.0°C | 12.6°C | 134 mm | 76% | 2.3 m/s | 5.5 |
| 2001 | 30.6°C | 24.2°C | 17.8°C | 36.1°C | 12.3°C | 97 mm | 66% | 2.1 m/s | 5.6 |
| 2000 | 30.8°C | 24.1°C | 17.4°C | 36.7°C | 11.7°C | 74 mm | 67% | 2.7 m/s | 5.6 |
| 1999 | 27.9°C | 21.6°C | 15.4°C | 32.2°C | 11.4°C | 100 mm | 68% | 2.2 m/s | 5.6 |
| 1998 | 27.5°C | 22.5°C | 17.6°C | 31.3°C | 13.7°C | 93 mm | 81% | 2 m/s | 5.4 |
| 1997 | 27.6°C | 22.0°C | 16.3°C | 35.4°C | 11.5°C | 152 mm | 74% | 2.3 m/s | 5 |
| 1996 | 28.9°C | 22.9°C | 16.9°C | 34.1°C | 13.2°C | 43 mm | 70% | 2.1 m/s | 5.7 |
| 1995 | 29.3°C | 24.8°C | 20.4°C | 32.5°C | 14.6°C | 105 mm | 82% | 1.7 m/s | 5.5 |
| 1994 | 27.3°C | 21.1°C | 14.9°C | 32.4°C | 8.6°C | 101 mm | 74% | 2.3 m/s | 5 |
| 1993 | 26.8°C | 22.6°C | 18.4°C | 31.2°C | 12.6°C | 159 mm | 86% | 2 m/s | 5 |
| 1992 ❄️ | 24.6°C | 18.9°C | 13.3°C | 29.1°C | 9.1°C | 31 mm | 78% | 2.2 m/s | 5.5 |
| 1991 | 29.6°C | 23.5°C | 17.5°C | 37.1°C | 13.3°C | 92 mm | 66% | 2.1 m/s | 5.3 |
| 1990 | 26.6°C | 21.5°C | 16.4°C | 32.0°C | 9.5°C | 105 mm | 80% | 1.9 m/s | 5.5 |
| 1989 | 29.7°C | 23.7°C | 17.6°C | 36.0°C | 11.1°C | 117 mm | 66% | 2.3 m/s | 5.4 |
| 1988 🔥 | 33.5°C | 26.6°C | 19.7°C | 40.3°C | 9.4°C | 56 mm | 54% | 2.6 m/s | 5.5 |
| 1987 | 29.6°C | 23.5°C | 17.3°C | 37.4°C | 10.5°C | 114 mm | 69% | 2.5 m/s | 5.1 |
| 1986 | 26.5°C | 20.2°C | 13.9°C | 32.9°C | 6.3°C | 34 mm | 69% | 2.2 m/s | 5.5 |
| 1985 | 26.1°C | 20.5°C | 15.0°C | 30.1°C | 9.1°C | 110 mm | 78% | 2.1 m/s | 4.9 |
| 1984 | 30.1°C | 23.6°C | 17.0°C | 37.8°C | 9.6°C | 26 mm | 66% | 2.1 m/s | 5.5 |
| 1983 | 32.4°C | 26.0°C | 19.5°C | 38.7°C | 12.5°C | 71 mm | 65% | 2.1 m/s | — |
| 1982 | 26.3°C | 20.8°C | 15.4°C | 31.4°C | 8.9°C | 89 mm | 78% | 2.1 m/s | — |
| 1981 🌧️ | 25.7°C | 21.1°C | 16.4°C | 29.1°C | 9.9°C | 205 mm | 83% | 2.2 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 28.5°C with lows near 17.2°C (mean 22.9°C), based on 45 years of NASA POWER data.
August averages 92 mm of rainfall in Normal, a relatively wet time of year. The wettest on record was 205 mm in 1981.
The hottest August reached 40.3°C in 1988. The coldest dipped to 6.3°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1°C. Daytime highs moved from 28.1°C to 29.2°C and overnight lows from 16.7°C to 17.6°C over the same span.
August is one of the warmer months of the year in Normal and a relatively wet time of year, so plan for around 28.5°C daytime highs and 17.2°C at night.
Not quite — August is the 11th coolest month in Normal, averaging 22.9°C.
For August in Normal, pack light layers you can adjust through the day, with typical highs of 28.5°C and lows of 17.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 73% — moderately humid.
Average wind speed in August is 2.2 m/s. The windiest August on record averaged 2.7 m/s (2000).
The wettest August on record was 1981 with 205 mm. On average, August sees 92 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Normal behaves each August, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for August specifically, along with year-by-year records and how the month has changed over the decades.
